米非司酮和米索前列醇用作药物流产的机制，正确的是（） A.与孕

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问题单项选择题

米非司酮和米索前列醇用作药物流产的机制，正确的是（）

A.与孕酮竞争孕激素受体从而阻断孕酮的作用

B.作用于滋养细胞使其坏死

C.降低孕酮的活性

D.促使胚胎基因突变而死亡

E.引起胚胎着床部位缺血

答案

参考答案：A

完形填空

小题1:—Hi! Sam, how are you doing?

—________.

A. That’s OK

B. Very well, thanks

C. Never mind

小题2:—I think there is too much rain this spring.

—________. It causes many floods.

A. I agree with you

B. I’m not sure

C. I’m all right

小题3:—Don’t be late again.

—________. I will be on time next time.

A. Yes, I will

B. No, I don’t

C. Sorry, I won’t

小题4:—I dare not speak English in class.

—________. You should believe in yourself.

A. That’s all right

B. Don’t be shy

C. That’s nothing

小题5:—________?

—Sure. We’d like some rice, chicken and vegetable soup.

A. May I come in

B. May I go with you

C. May I take your order

单项选择题

关于字节I/O流，下列叙述不正确的是（）。

A．DB包括DBS和DBMS

B．DBS包括DB和DBMS

C．DBMS包括DB和DBS

D．3者属于平级关系